Controller display shows E01 and the softener does not start regeneration

Safety first: Close the main water supply before disconnecting any hoses. If the unit is hard‑plumbed, isolate with the upstream shut‑off valves. Disconnect power before opening the control head.

• Check inlet valve: Verify the Cillit softener’s dedicated inlet stop valve is fully open. Many installations have a small quarter‑turn ball valve before the softener—ensure the handle is parallel to the pipe.
• Inspect inlet strainer: Most Cillit control valves (e.g. Cillit Aquadial / Cillit HS series) have a mesh strainer at the inlet port. Close inlet/outlet valves, relieve pressure via a nearby tap, then unscrew the inlet union and remove the strainer. Rinse under running water and brush off debris. Reinstall carefully, ensuring the O‑ring is seated.
• Check pressure: Confirm mains pressure is within the range specified on the Cillit rating plate (typically 1.5–8 bar). If pressure is low, the unit may not detect flow; consult a plumber if house pressure is inadequate.
• Inspect hoses/pipes: If flexible hoses are used, check for kinks or crushing behind the unit or cabinet. Straighten or replace damaged hoses.
• Reset the error: Restore water and power, then follow the Cillit control panel instructions to clear E01 (usually by pressing and holding the RESET or PROGRAM key for several seconds). Run a manual regeneration and confirm normal operation.